Chapter 4 Flashcards Preview

Species

is a set of individuals that can mate and produce fertile offspring

Biomass

large regions such as forests, deserts, and grasslands with distinct climates and certain species (especially vegetation) adapted to them

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Fossils

mineralized or petrified replicas of skeletons, bones, teeth, shells, leaves, and seeds, or impressions of such items found in rocks

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Biological Evolution

the process whereby earth’s life changes over time through changes in the genetic characteristics of populations

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Theory of Evolution

all species descended from earlier, ancestral species

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Natural selection

in which individuals with certain traits are more likely to survive and reproduce under a particular set of environmental conditions than are those without the traits

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Mutations

random changes in the DNA molecules

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Adaptation

The favored individuals possess heritable traits that give them some advantage overother individuals in a given population

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Differential Reproduction

which enables individuals with the trait to produce more surviving offspring than other members of the population produce

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Speciation

one species splits into two or more different species

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Geographic Isolation

occurs when different groups of the same population of a species become physically isolated from one another for a long period of time

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Reproductive Isolation

mutation and change by natural selection operate independently in the gene pools of geographically isolated populations

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Extinction

process in which an entire species ceases to exist (biological extinction) or a population of a species becomes extinct over a large region, but not globally

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Endemic Species

Species that are found in only one area

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Background Extinction

species have disappeared at a low rate

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Mass Extinction

significant rise in extinction rates above the background level

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Species Diversity

the number and variety of species it contains

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Ecological Niche

Scientists describe the role that a species plays in its ecosystem

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Generalists Species

have broad niches

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Specialists Species

occupy narrow niches

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Native Species

are those species that normally live and thrive in a particular ecosystem

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Nonnative Species

Other species that migrate into, or are deliberately or accidentally introduced into, an ecosystem

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Indicator Species

Species that provide early warnings of damage to a community or an ecosystem

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Keystone Species

species whose roles have a large effect on the types and abundance of other species in an ecosystem

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Foundation Species

species that play a major role in shaping their communities by creating and enhancing their habitats in ways that benefit other species

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Biodiversity

the variety of the earth’s species, or varying life-forms, the genes they contain, the ecosystems in which they live, and the ecosystem processes of energy flow and nutrient cycling that sustain all life